underwater
underwater-vehicle
underway
underwear
underwindow
underwood
underwrapper
undesired
undestructive
undetectable
  undetected
undetection
undetermined
undeveloped
undiluted
undimensional
undirected
undiscovered
undistorted
undisturbed
undo

    undetected broken tool

     инструмент со скрытым дефектом

     инструмент с невыявленной поломкой